Technical Wiring harness problems and fault lights

[PerttiE]

The Fiat repair shop suspects that there is a problem in the wiring harness between the ABS unit and the gearbox in my motorhome because the ABS unit is not receiving speed information from the gearbox (my car has a comfortmatic "automatic" gearbox). The gearbox temperature information is also abnormal. This causes the ABS and other fault lights to come on in the instrument cluster, especially in cold weather. If I then run the engine for 15-30 minutes (depending on the outside temperature) and turn it off and then start it again, the warning lights do not stay on and everything works normally. On the other hand, when the air is warm above +20-25c and the car is in a sunny place, the warning lights do not stay on and everything works normally. The car has only been driven 58,000 km and it is a 2013 model.
I would like to ask if anyone has any information on the price/replacement of such a wiring harness or experience with a similar fault?

 

[the green vanper]

Hello,

The x250 Ducatos (2006-2014) are know to develop strange electrical issues due to water ingress into the engine bay.

The other common problem is earthing issues.

Start by finding on the forum the earths (+ eventually power supplies) wiring diagrams. Replace the cables - especially the body to engine / gearbox one (they tend to rot on the inside, so it's hard to see at first glance) and be sure there's no problem on the body earthing point - migth the rusted around.

And information about how and where the water gets into the engine bay. Find the damage if there's one.

Connect MultiEcuScan or AlfaOBD with the appropriate interface to check the errors the van communicates.

 

[Communicator]

It is my understanding that on vehicles fitted with ABS, the speed signal is taken from the ABS sensors on the wheels. This does not seem to fit with "the ABS unit not receiving the speed information from the gearbox" as suggested in post #1?

I was thinking that perhaps I was becoming obsessed with the "rusty junction" syndrome, and hesitated to suggest it. While I know that it occurs close to the engine ecu, I do not know how it would affect other processors, except perhaps if the canbus has suffered. This would perhaps show on a diagnostic test, as suggested in post #2.

Given the statement that the faults disappear if the vehicle has been parked in a sunny location, or when the engine has been warmed up, it does seem that moisture may be involved. Given the relative simplicity of the check for "rusty junction", it may well be worth eliminating it before proceeding further.

The so called "rusty junction" refers to a section of harness below the LHS headlamp, rubbing on a tubular frame member. The paint is rubbed off the frame member, abrasive rust takes hold, and further damage to the harness occurs.

 

[AsdaPricey]

Sticking with the temperature theme, did any of the early Euro 5 X250 become subject to the ecu/emissions including the ambient temperature reading from the wing mirror temp sensor? i.e, all manner of running issues/fault codes if the ambient temperature reading is incorrect or missing?

 

[PerttiE]

Hello,

The x250 Ducatos (2006-2014) are know to develop strange electrical issues due to water ingress into the engine bay.

The other common problem is earthing issues.

Start by finding on the forum the earths (+ eventually power supplies) wiring diagrams. Replace the cables - especially the body to engine / gearbox one (they tend to rot on the inside, so it's hard to see at first glance) and be sure there's no problem on the body earthing point - migth the rusted around.

And information about how and where the water gets into the engine bay. Find the damage if there's one.

Connect MultiEcuScan or AlfaOBD with the appropriate interface to check the errors the van communicates.

Thanks for your reply, the repair shop will measure the wiring harness and if a fault is found, they will be able to "bypass" the faulty cable .

 

[PerttiE]

It is my understanding that on vehicles fitted with ABS, the speed signal is taken from the ABS sensors on the wheels. This does not seem to fit with "the ABS unit not receiving the speed information from the gearbox" as suggested in post #1?

I was thinking that perhaps I was becoming obsessed with the "rusty junction" syndrome, and hesitated to suggest it. While I know that it occurs close to the engine ecu, I do not know how it would affect other processors, except perhaps if the canbus has suffered. This would perhaps show on a diagnostic test, as suggested in post #2.

Given the statement that the faults disappear if the vehicle has been parked in a sunny location, or when the engine has been warmed up, it does seem that moisture may be involved. Given the relative simplicity of the check for "rusty junction", it may well be worth eliminating it before proceeding further.

The so called "rusty junction" refers to a section of harness below the LHS headlamp, rubbing on a tubular frame member. The paint is rubbed off the frame member, abrasive rust takes hold, and further damage to the harness occurs.

It is my understanding that on vehicles fitted with ABS, the speed signal is taken from the ABS sensors on the wheels. This does not seem to fit with "the ABS unit not receiving the speed information from the gearbox" as suggested in post #1?

I was thinking that perhaps I was becoming obsessed with the "rusty junction" syndrome, and hesitated to suggest it. While I know that it occurs close to the engine ecu, I do not know how it would affect other processors, except perhaps if the canbus has suffered. This would perhaps show on a diagnostic test, as suggested in post #2.

Given the statement that the faults disappear if the vehicle has been parked in a sunny location, or when the engine has been warmed up, it does seem that moisture may be involved. Given the relative simplicity of the check for "rusty junction", it may well be worth eliminating it before proceeding further.

The so called "rusty junction" refers to a section of harness below the LHS headlamp, rubbing on a tubular frame member. The paint is rubbed off the frame member, abrasive rust takes hold, and further damage to the harness occurs.

It is my understanding that on vehicles fitted with ABS, the speed signal is taken from the ABS sensors on the wheels. This does not seem to fit with "the ABS unit not receiving the speed information from the gearbox" as suggested in post #1?

I was thinking that perhaps I was becoming obsessed with the "rusty junction" syndrome, and hesitated to suggest it. While I know that it occurs close to the engine ecu, I do not know how it would affect other processors, except perhaps if the canbus has suffered. This would perhaps show on a diagnostic test, as suggested in post #2.

Given the statement that the faults disappear if the vehicle has been parked in a sunny location, or when the engine has been warmed up, it does seem that moisture may be involved. Given the relative simplicity of the check for "rusty junction", it may well be worth eliminating it before proceeding further.

The so called "rusty junction" refers to a section of harness below the LHS headlamp, rubbing on a tubular frame member. The paint is rubbed off the frame member, abrasive rust takes hold, and further damage to the harness occurs.

Thanks for your reply, I gave the repair shop a tip to check the wiring harness under the headlight in question on the left side.

 

[PerttiE]

Sticking with the temperature theme, did any of the early Euro 5 X250 become subject to the ecu/emissions including the ambient temperature reading from the wing mirror temp sensor? i.e, all manner of running issues/fault codes if the ambient temperature reading is incorrect or missing?

Thanks for your tip, I'll pass this information on to the repair shop so they can check the temperature sensor as well